According to Worthplaying, patch 1.01 for Dark Messiah has been released via Steam on Friday. I can confirm that an update was delivered for the multiplayer part on my computer, but I did not try to update the single-player part as I did not experience any major problem yet. I guess that standard patches will be posted on the Ubisoft FTP very soon. A lenghty list of fixes for both single-player and multiplayer can be found by clicking on the link above.